1. Field of the Invention
The present techniques relate to a Group III nitride semiconductor light-emitting device and to a method for producing the device. More particularly, the techniques relate to a Group III nitride semiconductor light-emitting device having a current-blocking layer and to a method for producing the device.
2. Background Art
In a Group III nitride semiconductor light-emitting device, current tends to flow a region directly under the p-electrode, while current flow is impeded in a region away from the p-electrode. Due to the localization of current flow, the overall emission efficiency of the light-emitting device may be suppressed.
In one solution for preventing such localization of current flow, a current-blocking layer is placed directly under the p-electrode. For example, Patent Document 1 discloses a technique in which a transparent insulating film is formed as a current-blocking layer (see, for example, paragraphs [0017] and [0018], and FIG. 1 of Patent Document 1). By virtue of the current-blocking layer, light emission can be caused to occur selectively in a light-emitting layer (see, for example, paragraph [0004] of Patent Document 1).
Patent Document 2 discloses a light-emitting device of a laser lift-off type. In the light-emitting device, a current-blocking layer is disposed between the p-type GaN layer and the p-electrode. The current-blocking layer serves as a distributed Bragg reflector (DBR). The current-blocking layer diffuses current, and the distributed Bragg reflector (DBR) reflects light emitted from the light-emitting layer toward the light extraction face on the n-type semiconductor layer side (see, for example, paragraphs [0010] and [0028] of Patent Document 2).
Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2008-192710
Patent Document 2: Japanese Patent Application Laid-Open (kokai) No. 2007-150310
Meanwhile, in some cases, a face-up-type light-emitting device, having a light-extraction face on the p-type semiconductor layer side, may be provided with a current-blocking layer also serving as a distributed Bragg reflector (DBR). In such case, the light emitted from the light-emitting layer toward the p-electrode is reflected by the distributed Bragg reflector (DBR), whereby the light is not absorbed by the p-electrode and is reflected toward the semiconductor layer. Although the light is not absorbed by the p-electrode, the light may be re-absorbed by the light-emitting layer. In order to suppress the re-absorption of light, the current-blocking layer also serving as a distributed Bragg reflector (DBR) preferably has a somewhat small size.
From another viewpoint, semiconductor light-emitting devices preferably attain sufficient current diffusion over a desired device region. For this purpose, the current-blocking layer preferably has a somewhat large size. However, when a wide-area current-blocking layer is formed so as to attain sufficient current diffusion, the light to be extracted to the outside is undesirably reflected toward the semiconductor layer.